Conventional field replaceable units often include circuitry such as light emitting diodes (LED""s), displays or buttons in a front plate accessible to an operator. This circuitry connects through printed circuit boards (PCBs) or cabling to a rear mounted connector. A complimentary connector for the front plate circuitry is located on a backplane, so that as the FRU is inserted into an enclosure, the FRU rear mounted connector, completing a circuit from the front of the unit to the rear of the unit, makes contact with this backplane connector. It has been recognised, however, that either of such FRU or backplane connectors may fail from time to time. In the case of the connector on the FRU, failure may simply require the replacement of the FRU. If the FRU is a disk shuttlexe2x80x94the enclosed disk may in fact be re-used if required. On the other hand if the backplane connector fails, then the entire backplane may need to be removed and even replaced at an extremely high cost.
This problem has been recognised in the case of LED outputs and solved by the replacement of the backplane connector with a LED, cooperating with a light pipe running the length of the FRU through to an aperture in the front plate 12. A disk shuttle example, of such an FRU is fully described in US Pat. No. 6,050,658 the disclosure of which is incorporated herein by reference. When this disk shuttle is inserted in the rack enclosure, the light pipe lies in register with the LED, so that when the LED is on, the light pipe transmits this light through to the front plate, so displaying the state of the LED at the front of the rack enclosure. This solution, however, does not solve the original problem in the case of liquid crystal display (LCD) displays or button inputs which may be located on the front-plate and so at the very least different components would be required for input or output signals.
The use of conventional connectors for completing circuits between a rack backplane and field replaceable unit involves additional cost in manufacturing the backplane to include extra connector components; and cost of PCB or cable for carrying a signal through to the front of the unit. It also exposes a system to a number of possible errors due to a large number of components including: backplane connector, field replaceable unit connector and field replaceable unit PCB or cables.
The present invention seeks to mitigate these problems and others of the prior art.
According to the present invention, there is provided a field replaceable unit comprising: a housing having a front and a rear and being configured for sliding insertion into and out of a rack from its rear; and a connector for, in use, completing an electrical circuit from a backplane of said rack to a component of said field replaceable unit, said connector comprising a first rear projecting electrically conductive spring loaded member operative to engage an electrical pad on said backplane when said housing is inserted in said rack.
Preferably, the field replaceable unit incorporates a front plate removably attached to said housing and including said component, and said connector comprises a second front projecting electrically conductive spring loaded member electrically coupled to said first electrically conductive spring loaded member and operative, when said front plate is attached to said housing, to engage a second pad electrically coupled to said component and disposed behind said front plate.
Using the present invention, the possibility of having a faulty connection between, say a backplane, and the field replaceable unit is reduced and problems associated with such a faulty connection are mitigated as, if such a fault occurs, only the field replaceable unit incorporating the connector need be replaced, rather than possibly having to replace an entire backplane to which the field replaceable unit as well as many other devices connect.
Furthermore, using the invention requires only the provision of simple pads on the backplane, so reducing the cost of the backplane, as there is no need for connectors, PCB""s or cables.
The field replaceable unit of the invention can incorporate both input and output signal components using the same connectors so reducing manufacturing cost due to the reduced number of different parts required for a system.